How to Become a Star

At a distance of only 410 light-years, Barnard 68 is one of the nearest dark clouds, a so-called "Bok globule". Its size is about 12,500 AU (= 2 million million km), or just about the same as the so-called "Oort Cloud" of long-period comets that surrounds the solar system. The temperature of Barnard 68 is 16 Kelvin (-257 _C) and the total mass of the cloud is about twice that of the Sun.
By means of instruments at the Very Large Telescope at Paranal, astronomers found a total of about 3700 background stars (of which over 1000 can only be seen at infrared wavelengths).
Careful measurements of the colours of these stars and hence, the degree of obscuration, allowed the most finely sampled and most accurate mapping of the dust distribution inside a dark cloud ever performed. It was found that this dependance is almost exactly as that predicted for a sphere in which the opposite forces of gravity and internal pressure closely balance each other. Nevertheless, it is also evident that Barnard 68 is only marginally stable and is on the verge of collapse. The astronomers suggest that Barnard 68 may be the precursor of an isolated and sparsely populated association of low-mass solar-like stars.